[Cross-posted to the mainframe assembler list]

[This is in two parts because of restrictions on posting
 size for the assembler list.]


Based on some earlier posts on the mainframe assembler list,
I have been researching the semiprivileged instructions to
see which ones might be useful for application programs
(programs written to accomplish corporate work: problem state,
only standard interfaces and APIs used).

The PoPs says, on page 5-24 in the PDF version (dz9zr008.pdf /
SA22-7832-08), "there are 23 semiprivilged instructions".

There is a table, Figure 5-6 on pp. 5-28/5-29, that purportedly
includes all the semiprivileged instructions along with some
other instructions that use authorization messages. If you stick
with the 23 semiprivilged instructions, you get these:

BAKR    - Branch and Stack
BSA     - Branch and Set Authority

EPAR    - Extract Primary ASN
EPAIR   - Extract Primary ASN and Instance
ESAR    - Extract Secondary ASN
ESAIR   - Extract Secondary ASN and Instance

IAC     - Insert Address space Control
IPK     - Insert PSW Key
IVSK    - Insert Virtual Storage Key

MVCDK   - Move Characters with Destination Key
MVCK    - Move Characters with Key (not shown in Figure 5-6 on pp. 5-28/5-29)
MVCOS   - Move Characters with Optional Specifications
MVCP    - Move Characters to Primary
MVCS    - Move Characters to Secondary
MVCSK   - Move Characters with Source Key

PC      - Program Control
PR      - Program Return
PT      - Program Transfer
PTI     - Program Transfer with Instance

RP      - Resume Program

SAC     - Set Address space Control
SACF    - Set Address space Control Fast
SPKA    - Set PSW Key from Address



Some other interesting instructions in this table:

BSG     - Branch in Subspace Group
EREG    - Extract stacked REGisters (32 bits)
EREGG   - Extract stacked REGisters Grande (64-bits)
ESTA    - Extract stacked STAte
LPTEA   - Load Page Table Entry Address
MSTA    - Modify stacked STAte
SSAR    - Set Secondary ASN
SSAIR   - Set Secondary ASN with Instance
STRAG   - Store Real Address  p
TAR     - Test Access         p
TPROT   - Test PROTection     p

  ('interesting' in the sense they are not
   semiprivileged and the first eight are
   not privileged either, but they are
   described in the chapter on Control
   Instructions: so are they 'general'
   instructions? I think not, but it's hard
   to say.)


My focus: are these first eight instructions useful
for applications programmers?


--

Kind regards,

-Steve Comstock
The Trainer's Friend, Inc.

303-355-2752
http://www.trainersfriend.com

* To get a good Return on your Investment, first make an investment!
  + Training your people is an excellent investment

* Try our tool for calculating your Return On Investment
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